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51S-61P-31P-41?

Posted By: Nack Ballard
Date: Saturday, 9 July 2011, at 6:44 p.m.

In Response To: 51S-61P-31P-41? (mtuhtan)

51S-41

61P-51S-41

For the standard 51S-41 reply shown in the left-hand position, two plays are very close: K (Kill, 6/2*/1*) and D (Down, 13/8). To be exact, K is better by .012 in an aggregate of rollouts. If you knew K is better but had no idea by how much, then you had a much smaller chance of making the correct adjustment in your game position (shown below).

In the right-hand position, a play is pre-added for blue: 61P-51S-41. The midpoint has one fewer checker and there is another checker in the zone, both factors arguing for K; however, Blue's priming plan is stronger and his 8pt is stripped, both factors arguing for D. (The U play is in the mix, too, but that's unimportant for our purposes here.)

On balance (on the right) the K/D difference of .012 is more than wiped out, and D is a better play. However, an exact judgment is not necessary; if you just conclude that the decision is somewhat close on the right (because the decision is close on the left), that is adequate for determining the correct play in your fourth roll position (shown below).

Pre-adding 31P for White (her order of plays makes no difference), we have your game position. Now what? White's board is substantially stronger, so the cost of getting hit is substantially greater. Just play D.

51S-61P-31P-41

Nack

Messages In This Thread

• 51S-61P-31P-41?
  mtuhtan -- Saturday, 9 July 2011, at 4:57 p.m.
  • 51S-61P-31P-41?
    garyo -- Saturday, 9 July 2011, at 5:34 p.m.
  • 51S-61P-31P-41?
    Timothy Chow -- Saturday, 9 July 2011, at 5:39 p.m.
  • 51S-61P-31P-41?
    Nack Ballard -- Saturday, 9 July 2011, at 6:44 p.m.
    • Nack's Genius Analysis
      Paul Weaver -- Saturday, 9 July 2011, at 8:43 p.m.
      • Nack's Genius Analysis
        mtuhtan -- Saturday, 9 July 2011, at 9:02 p.m.
        • Nack's Genius Analysis
          Paul Weaver -- Saturday, 9 July 2011, at 9:58 p.m.
          • Nack's Genius Analysis
            mtuhtan -- Sunday, 10 July 2011, at 6:06 a.m.
      • Nack's Genius Analysis
        John O'Hagan -- Sunday, 10 July 2011, at 12:02 a.m.
      • Nack's Genius Analysis
        Timothy Chow -- Sunday, 10 July 2011, at 12:30 a.m.
        • Nack's Genius Analysis
          Higonefive -- Sunday, 10 July 2011, at 9:41 a.m.
      • Nack's Genius Analysis
        Nack Ballard -- Sunday, 10 July 2011, at 1:27 a.m.
  • 51S-61P-31P-41?
    Higonefive -- Sunday, 10 July 2011, at 9:32 a.m.
  • 51S-61P-31P-41 - Rollout
    mtuhtan -- Monday, 18 July 2011, at 4:32 p.m.